1. Field of the Invention
The invention relates to an indicating device, more particularly to a test lead socket indicating device for a volt-ohm-milliameter.
2. Description of the Related Art
Referring to FIG. 1, a conventional volt-ohm-milliameter (VOM) is shown to have rotary input (11) [a push button input may also be used] and a pair of test leads (12, 13) for connecting the VOM to a circuit undergoing testing. The VOM may be operated in a voltage, current or resistance measuring mode. The VOM is provided with a common input socket (14), a voltage socket (15), a resistance socket (17) and a current socket (16). The test lead (12) has one end connected to the common input socket (14). The test lead (13) has one end connected to one of the remaining sockets (15, 16, 17), depending upon the desired measuring mode of the VOM.
A main drawback of the conventional VOM is that connection of the test lead (13) to an incorrect one of the sockets (15, 16, 17) easily occurs. For example, the output terminals of a test circuit are short-circuited if the test lead (13) is accidentally connected to the current socket (16) when the VOM is used to measure the output voltage of the test circuit. The short-circuit current which is produced can cause damage to the test circuit and to the VOM.